1 //===--- GlobalModuleIndex.h - Global Module Index --------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the GlobalModuleIndex class, which manages a global index
11 // containing all of the identifiers known to the various modules within a given
12 // subdirectory of the module cache. It is used to improve the performance of
13 // queries such as "do any modules know about this identifier?"
15 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_CLANG_SERIALIZATION_GLOBAL_MODULE_INDEX_H
17 #define LLVM_CLANG_SERIALIZATION_GLOBAL_MODULE_INDEX_H
19 #include "llvm/ADT/DenseMap.h"
20 #include "llvm/ADT/OwningPtr.h"
21 #include "llvm/ADT/SmallPtrSet.h"
22 #include "llvm/ADT/SmallVector.h"
23 #include "llvm/ADT/StringMap.h"
24 #include "llvm/ADT/StringRef.h"
28 class BitstreamCursor;
38 namespace serialization {
42 using llvm::SmallVector;
43 using llvm::SmallVectorImpl;
44 using llvm::StringRef;
45 using serialization::ModuleFile;
47 /// \brief A global index for a set of module files, providing information about
48 /// the identifiers within those module files.
50 /// The global index is an aid for name lookup into modules, offering a central
51 /// place where one can look for identifiers determine which
52 /// module files contain any information about that identifier. This
53 /// allows the client to restrict the search to only those module files known
54 /// to have a information about that identifier, improving performance. Moreover,
55 /// the global module index may know about module files that have not been
56 /// imported, and can be queried to determine which modules the current
57 /// translation could or should load to fix a problem.
58 class GlobalModuleIndex {
59 /// \brief Buffer containing the index file, which is lazily accessed so long
60 /// as the global module index is live.
61 llvm::OwningPtr<llvm::MemoryBuffer> Buffer;
63 /// \brief The hash table.
65 /// This pointer actually points to a IdentifierIndexTable object,
66 /// but that type is only accessible within the implementation of
67 /// GlobalModuleIndex.
68 void *IdentifierIndex;
70 /// \brief Information about a given module file.
72 ModuleInfo() : File(), Size(), ModTime() { }
74 /// \brief The module file, once it has been resolved.
77 /// \brief The module file name.
80 /// \brief Size of the module file at the time the global index was built.
83 /// \brief Modification time of the module file at the time the global
87 /// \brief The module IDs on which this module directly depends.
88 /// FIXME: We don't really need a vector here.
89 llvm::SmallVector<unsigned, 4> Dependencies;
92 /// \brief A mapping from module IDs to information about each module.
94 /// This vector may have gaps, if module files have been removed or have
95 /// been updated since the index was built. A gap is indicated by an empty
97 llvm::SmallVector<ModuleInfo, 16> Modules;
99 /// \brief Lazily-populated mapping from module files to their
100 /// corresponding index into the \c Modules vector.
101 llvm::DenseMap<ModuleFile *, unsigned> ModulesByFile;
103 /// \brief The set of modules that have not yet been resolved.
105 /// The string is just the name of the module itself, which maps to the
107 llvm::StringMap<unsigned> UnresolvedModules;
109 /// \brief The number of identifier lookups we performed.
110 unsigned NumIdentifierLookups;
112 /// \brief The number of identifier lookup hits, where we recognize the
114 unsigned NumIdentifierLookupHits;
116 /// \brief Internal constructor. Use \c readIndex() to read an index.
117 explicit GlobalModuleIndex(llvm::MemoryBuffer *Buffer,
118 llvm::BitstreamCursor Cursor);
120 GlobalModuleIndex(const GlobalModuleIndex &) LLVM_DELETED_FUNCTION;
121 GlobalModuleIndex &operator=(const GlobalModuleIndex &) LLVM_DELETED_FUNCTION;
124 ~GlobalModuleIndex();
126 /// \brief An error code returned when trying to read an index.
128 /// \brief No error occurred.
130 /// \brief No index was found.
132 /// \brief Some other process is currently building the index; it is not
135 /// \brief There was an unspecified I/O error reading or writing the index.
139 /// \brief Read a global index file for the given directory.
141 /// \param Path The path to the specific module cache where the module files
142 /// for the intended configuration reside.
144 /// \returns A pair containing the global module index (if it exists) and
146 static std::pair<GlobalModuleIndex *, ErrorCode>
147 readIndex(StringRef Path);
149 /// \brief Returns an iterator for identifiers stored in the index table.
151 /// The caller accepts ownership of the returned object.
152 IdentifierIterator *createIdentifierIterator() const;
154 /// \brief Retrieve the set of modules that have up-to-date indexes.
156 /// \param ModuleFiles Will be populated with the set of module files that
157 /// have been indexed.
158 void getKnownModules(SmallVectorImpl<ModuleFile *> &ModuleFiles);
160 /// \brief Retrieve the set of module files on which the given module file
161 /// directly depends.
162 void getModuleDependencies(ModuleFile *File,
163 SmallVectorImpl<ModuleFile *> &Dependencies);
165 /// \brief A set of module files in which we found a result.
166 typedef llvm::SmallPtrSet<ModuleFile *, 4> HitSet;
168 /// \brief Look for all of the module files with information about the given
169 /// identifier, e.g., a global function, variable, or type with that name.
171 /// \param Name The identifier to look for.
173 /// \param Hits Will be populated with the set of module files that have
174 /// information about this name.
176 /// \returns true if the identifier is known to the index, false otherwise.
177 bool lookupIdentifier(StringRef Name, HitSet &Hits);
179 /// \brief Note that the given module file has been loaded.
181 /// \returns false if the global module index has information about this
182 /// module file, and true otherwise.
183 bool loadedModuleFile(ModuleFile *File);
185 /// \brief Print statistics to standard error.
188 /// \brief Write a global index into the given
190 /// \param FileMgr The file manager to use to load module files.
192 /// \param Path The path to the directory containing module files, into
193 /// which the global index will be written.
194 static ErrorCode writeIndex(FileManager &FileMgr, StringRef Path);